The U.S. Immigration and Customs Enforcement agency declined to identify which companies were targeted in its expanding crackdown on hiring of illegal workers.

But the agency said they included small businesses as well as name brands in 17 sectors of the economy, including agriculture and food, financial services, commercial nuclear reactors, drinking water and water treatment, postal and shipping, healthcare and transportation.

“The inspections will touch on employers of all sizes and in every state in the nation, with an emphasis on businesses related to critical infrastructure and key resources,” ICE said in a statement.

The agency said the focus on businesses tied to critical infrastructure was part of the agency’s mission to focus on threats to national security and public safety. A similar audit on such industries was done in November 2009.

The new audit notices from ICE coincided with a move in Congress to require all U.S. employers to adopt a government screening program designed out to ferret out illegal workers.

Michael Wildes, an immigration lawyer at Wildes & Weinberg in New York, said he was retained by a company minutes after ICE agents showed up there on Wednesday. He declined to name his client or specify the industry in which it operates.

He suggested Wednesday’s move was politically motivated.

“There’s an election around the corner, there are scores of people who are finally seeing that the deafening silence in Washington on immigration needs to be dealt with,” he said.

“Sending out a message like this is a good talking point and looks pretty on TV, but effectively doesn’t do anything,” Wildes said, adding that he understood 28 companies in New Jersey alone were singled out by ICE on Wednesday.

E-VERIFY LINK?

The enforcement action came a day after U.S. Representative Lamar Smith, a Texas Republican and chairman of the House Judiciary Committee, introduced a bill that would require all U.S. employers to use the government’s E-Verify system.

E-Verify is an online system that uses data from U.S Department of Homeland Security and Social Security Administration records to confirm whether prospective employees are eligible to work.

Smith said broad adoption of E-Verify would help ensure that jobs are reserved for citizens and legal workers.

The issue of immigration is expected to play a major role in the 2012 election in which President Barack Obama and his Republican challengers are seeking the pivotal Hispanic vote.

The House Judiciary subcommittee on immigration policy and enforcement held a hearing on Smith’s bill on Wednesday. It was not immediately clear whether the legislation would advance.

Participation in E-Verify is voluntary for most companies, but there are exceptions. The program is mandatory for most employers in Arizona and Mississippi under state law, and U.S. regulations require firms with federal contracts or subcontracts to use the system.

The U.S. Supreme Court recently endorsed an Arizona law requiring employers to use E-Verify.

Immigrant rights groups and unions are among E-Verify’s most vocal critics, and government officials acknowledge that the system has room for improvement. An undocumented individual who steals the identity of a U.S. citizen would not be flagged by the network, for example.

“The idea that this E-Verify bill will protect workers and offer more jobs to unemployed Americans is hogwash,” said Jorge-Mario Cabrera, spokesman for the Coalition for Humane Immigrant Rights of Los Angeles (CHIRLA).

During its immigration audits, ICE inspectors review hiring records to find out whether the businesses have violated U.S. employment laws by hiring undocumented workers.

Critics of the government’s focus on enforcement say it adds burdensome costs and the threat of business disruption without providing any long-term solutions.

“Employers are bearing the burden of Congress refusing to act in a more comprehensive way on immigration reform,” said Eleanor Pelta, a partner in the Washington office of Morgan, Lewis & Bockius and incoming president of the American Immigration Lawyers Association.

The latest ICE action brings the total number of workplace audits for this fiscal year to 2,338, surpassing the previous year’s total, ICE said.

Ray Gilmer, spokesman for the United Fresh Produce Association, said ICE audits of farm employers have been on the rise for months.

“The introduction of mandatory E-Verify legislation Tuesday, combined with the heightened level of audits, presents a serious threat to farms around the country,” he said. (Editing by Xavier Briand)